In some code I am developing I had occasion to change the type of a
variable. This made the value put_user was putting to user space
wrong. But the code continued to build cleanly without errors.
Introducing a temporary fixes this problem and at least with gcc-3.3.5
does not cause gcc any problems with optimizing out the temporary.
gcc-4.x using SSA internally ought to be even better at optimizing out
temporaries, so I don't expect a temporary to become a problem.
Especially because in all correct cases the types on both sides of the
assignment to the temporary are the same.
Signed-off-by: Eric W. Biederman <[email protected]>
---
include/asm-i386/uaccess.h | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
dd1215e541bfe2ed94a902f7fb263ca44b7e8afa
diff --git a/include/asm-i386/uaccess.h b/include/asm-i386/uaccess.h
index 3f1337c..1641613 100644
--- a/include/asm-i386/uaccess.h
+++ b/include/asm-i386/uaccess.h
@@ -198,12 +198,13 @@ extern void __put_user_8(void);
#define put_user(x,ptr) \
({ int __ret_pu; \
__chk_user_ptr(ptr); \
+ __typeof__(*(ptr)) __pu_val = x; \
switch(sizeof(*(ptr))) { \
- case 1: __put_user_1(x, ptr); break; \
- case 2: __put_user_2(x, ptr); break; \
- case 4: __put_user_4(x, ptr); break; \
- case 8: __put_user_8(x, ptr); break; \
- default:__put_user_X(x, ptr); break; \
+ case 1: __put_user_1(__pu_val, ptr); break; \
+ case 2: __put_user_2(__pu_val, ptr); break; \
+ case 4: __put_user_4(__pu_val, ptr); break; \
+ case 8: __put_user_8(__pu_val, ptr); break; \
+ default:__put_user_X(__pu_val, ptr); break; \
} \
__ret_pu; \
})
--
1.1.5.g3480
-
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